EP3785463A1

EP3785463A1 - Method for federating at least two communication networks for mobile terminals and network capable of being federated

Info

Publication number: EP3785463A1
Application number: EP19719309.7A
Authority: EP
Inventors: Franck SCHOLLER; Jean-François Perez; Jean-Marc MONTENOT; Wannes VOSSEN
Original assignee: Airbus Defence and Space SAS
Current assignee: Airbus Defence and Space SAS
Priority date: 2018-04-27
Filing date: 2019-04-26
Publication date: 2021-03-03
Anticipated expiration: 2039-04-26
Also published as: US20210243615A1; FR3080731B1; US11375387B2; EP3785463B1; FR3080731A1; WO2019207090A1

Abstract

The invention relates to a method for federating at least two communication networks for mobile terminals by establishing a dedicated link between the two networks and then configuring one of the networks to use elements of the other network, in particular the user database and the communication policy manager.

Description

Method for federation of at least two communication networks for mobile terminals and federated network

TECHNICAL FIELD OF THE INVENTION The subject of the invention is a method of federation of at least two communication networks for mobile terminals.

The field of the invention is in particular that of tactical bubbles. More precisely, the field of the invention is that of the cooperation of at least two communication networks such as tactical bubbles. The field of the invention is also that of the continuity of mobile access in theaters of operations.

STATE OF THE ART

For sensitive mobile communications, means for securing said mobile communications based on a public LTE network are known. Sensitive mobile communications are, for example:

- Communications from law enforcement or civil security;

- Military communications;

- Communications from Vital Infrastructure Operators, for example power generation facilities;

-. . .

In the remainder of the document, intervention forces are understood to mean forces as mentioned above that are required to intervene on a theater of operations to resolve a crisis situation and the need to communicate in a secure manner anywhere is critical for the good resolution of the crisis situation. In the state of the art, the communications to be secured are in connection with a central orchestrator that protects for example access to a sensitive application. Communications are further performed using encrypted tunnels. This solution allows all known users of the Orchestrator to: - Connect to sensitive applications,

- Communicate between them,

- Move while maintaining communications, it is indeed known to perform a handover in a mobile network where the entire LTE structure is determined, which is the case of public networks or fixed.

In the state of the art secure communications are dependent on the availability of a public mobile network. But this network can be made unavailable for multiple reasons:

Destruction of part of the public infrastructure, in particular the radio part by the visibility of the base stations;

Saturation of the infrastructure, for example, when the police intervene in one place, their presence and the reason for their presence is likely to arouse the curiosity and the anxiety of the people present in the neighborhood which will increase the flow of communications and over-consumption of communication resources;

Scrambling communications or attacking the public communication infrastructure;

Need to intervene in an area not covered by the public network. This problem is, in the state of the art, partially addressed by the deployment of a tactical bubble. This deployment allows users of the Tactical Bubble to be independent of any other infrastructure for their communications.

TECHNICAL PROBLEM

However, with the solutions of the state of the art, new problems arise.

Thus, the response forces have tactical bubbles consisting of an autonomous LTE-type mobile communication network allowing user equipment referenced on this tactical network to communicate with each other in the field autonomously and securely. Each bubble has all the equipment of a LTE type mobile telecommunication network, especially the base station of the bubble tactical named eNodeB based on LTE technology, the user database named HSS (Home Subscriber Server) based on LTE technology, PCRF equipment, Packet Data Network Gateway (PGW) and SGW (Serving Gateway) service gateways, Mobility Management Entity (MME) and the Application Function (AF) entity for accessing application servers. Each bubble manages its own fleet of user equipment, access to radio resources and the establishment of communications between them and to business applications, through its equipment. Each bubble is configured to the most just according to the fleet of user equipment it must accommodate which allows the use of equipment with reduced capacity compared to the equipment of a standard public mobile telecommunication network, thus making them movable and transportable more easily and at a lower cost.

When several tactical bubbles of the intervention forces are deployed on the ground, these tactical bubbles can be brought to be positioned close to each other. This geographical proximity of the tactical bubbles induces several problems:

- Since the radio frequencies and the network identifier of these tactical bubbles are identical, their proximity causes interference in the coverage areas of the radio coverage that adversely affect the quality of communications;

- Each tactical bubble managing its own fleet of user equipment on a radio network of the same nature and the same spectrum, a user equipment referenced in a bubble A in the area of coverage of the bubble B will attempt to hang on bubble B without success because it is not referenced on the bubble A and once unhooked from the network of the bubble A it will not be able to reconnect automatically to the latter;

- Tactical bubbles can have identical configurations set in the factory (HSS with the same name, eNodeB parameterized identically for each bubble), this causes a number of network inconsistencies when these bubbles are located close to each other.

One of the solutions proposed by the prior art to solve the problem is to provision in the factory configuration of each tactical bubble, the whole of the fleet of user equipment and user profiles of the response forces. Thus, when the bubbles are close to each other, one of the bubbles is extinguished and the user equipment cling to the other tactical bubble maintained in operation. This approach, however, has several disadvantages:

- Each bubble must be provisioned with the total number of user equipment managed by the intervention forces and therefore requires equipment with the highest possible capabilities for each tactical bubble therefore very expensive and more difficult to transport.

- Switching user devices to the bubble held in operation causes the interruption of communications

- Finally, the switchover of the user equipment on the infrastructure of a single tactical bubble requires sharing access to the application servers of this bubble with all users of the network while in some cases the servers of application must be dedicated to a given tactical bubble and its access restricted exclusively to users of this tactical bubble.

SUMMARY OF THE INVENTION

The invention provides an answer to the above problems by allowing to federate one or more bubbles of mobile communication between them when they are close to each other, while:

- Guaranteeing the most accurate dimensioning of each tactical bubble,

- Ensuring the continuity of the communications without interruption of service and their essential quality for critical communications (during the establishment of the federation of the bubbles between them);

- By maintaining, if necessary, access to the application servers of each federated bubble to their respective users and

- By setting up bubble federation in a fully automatic way without the intervention of an operator.

Thanks to the invention, a first LTE type network and a second LTE type network can be deployed and connected together so that: - The mobile terminals connected to the two networks can communicate with each other;

- A terminal initially connected to the first network can connect to the second network and does not suffer loss of service or communication. The invention therefore allows a handover between two networks that did not know each other a priori (that is to say, for example, two mobile bubbles that do not know their structure a priori).

In these cases at least one of the two networks is a tactical bubble.

In this document a tactical bubble is a communication network for mobile terminals. Technically a tactical bubble is a cellular network with at least one radio cell, a backbone and an application or interface with the outside of the tactical bubble. A tactical bubble is intended to be mobile, at least mobile depending on communication needs. View of a User Terminal A Tactical Bubble is an LTE (Long Term Evolution for Long Term Evolution) network with a reduced number of base stations, usually one. In other words, a tactical bubble represents a mini-network similar to an operator network having a radio interface and allowing access to applications.

In this document, mobile communications is understood to mean communications via smartphone-type mobile terminals using LTE-type or newer communication networks. This type includes processing devices using LTE modems. This type also includes smart objects connected. In particular, it involves communications via an intermediate infrastructure: the LTE network.

In this document we say that we federate two communication networks such as two tactical bubbles, that is to say that we implement a method to federate radio modules and network core elements of the network. two initial bubbles to make them work as a single LTE network.

Each bubble has an orchestrator that allows the federation of tactical bubbles. Once the federated bubbles the group communications, video, data, applications, are possible in continuity throughout the area covered by the tactical bubbles. For example, for a situation requiring the intervention of a law enforcement team, for example the GIGN, and a team of civil security forces, for example firefighters, each team retains only access to its specific applications (eg a police database, video servers, etc ...), while allowing the other team to use its communication resources.

In the invention the two tactical bubbles are connected via a dedicated link. The bubbles agree on their role. A tactical bubble becomes master, the other slave. The election of a master bubble can be done according to several criteria, from first come first served, to taking into account the capacities of reception and treatment of each bubble (ie one will elect preferably the bubble capable of managing the most large number of user equipment). This allows, for example, to ensure that all users will be properly managed. The orchestrators of each tactical bubble map the transmissions by reconfiguring the networks and the local link.

The local link between the two tactical bubbles can be established by Wifi, LTE, ie a wireless connection. The local link can also be established via Ethernet or Fiber, ie a wired connection connecting the two tactical bubbles.

The subject of the invention is therefore a method of federation of a first communication network for mobile terminals and of a second communication network for mobile terminals, each communication network comprising a base station, a mobility manager, a gateway of service, a user database, a communication policy manager, a packet gateway each of said networks further comprising a router and an orchestrator, the method comprising the steps of:

- Establishment of a dedicated connection between the two communication networks by establishing a connection between the routers;

- Election of a master orchestrator among the network orchestrators to federate, defining a master network and a slave network;

- Update the master network user database from the user database of the slave network;

- Configuration of links between: o The service gateway of the master network and the mobility manager of the slave network;

o The service gateway of the slave network and the mobility manager of the master network;

o The mobility manager of the master network and the mobility manager of the slave network;

- Configuration of the slave network so that it uses:

o The user database of the master network;

o The communication policy manager of the master network.

According to embodiments the invention also has the following characteristics considered in all feasible technical combinations:

Each communication network has the same addressing scheme, the method comprising a step in which the router of each network is dynamically configured, by the orchestrator of its network, to perform an address translation for one reciprocal between the two. two networks;

- The method comprises the following steps:

o Updating each base station according to the neighboring base station;

o Update the list of service gateways for each network, each service gateway being associated with a zone code according to its home network.

o Update each mobility manager according to the configuration of the mobility manager of the neighboring network.

- The establishment of the dedicated connection is achieved by the use of a connection means belonging to the list of at least:

o A cable,

o A wireless connection.

- The communications made via the dedicated connection are done using a virtual private network.

- The use, by the slave network, elements of the master network is done by the configuration, in the slave networks of the secondary elements. - The configuration of the secondary elements is done by naming, the resolution of the names being configured by the orchestrator of the network at the time of the federation.

- A communication network for mobile terminals is a stand-alone network bubble.

- The election of the master orchestrator is done according to the processing capabilities of the bubble to which the orchestrator belongs.

- Access to the application functions of a bubble is maintained and is limited to its original users.

The invention also relates to a communication network for mobile terminals, said first network, adapted to be federated, with a second communication network for mobile terminals adapted to be federated, a communication network for mobile terminals adapted to be federated comprising a base station, a mobility manager, a service gateway, a user database, a communication policy manager, a packet gateway, each communication network further comprising a router and an orchestrator, said first network of communication being configured to:

- Establish a dedicated connection with a second communication network by establishing a dedicated connection between the router of the first network and the router of the second network;

- Elect a master orchestrator among the orchestrators of the first and second network to federate, defining a master network and a slave network;

- Configure links between:

o The service gateway of the master network and the mobility manager of the slave network;

o The packet gateway of the master network and the service gateway of the slave network; - Configure the slave network to use:

o The user database of the master network;

o The communication policy manager of the master network.

The communication network according to the invention may be an autonomous network bubble. LIST OF FIGURES

The figures are presented as an indication and in no way limit the invention. Different figures show identical elements with the same references. The figures show:

- Figure 1: a functional illustration of tactical bubbles to federate, before federation;

- Figure 2: a functional illustration of tactical bubbles to federate, after federation;

- Figure 3: an illustration of the steps of the method according to the invention;

- Figure 4: an illustration of the implementation of the invention for two tactical bubbles;

FIG. 5: an illustration of the implementation of the invention for two tactical bubbles, one of which proposes access to an external network;

- Figure 6: an illustration of the implementation of the invention for three tactical bubbles;

FIG. 7: an illustration of a federation according to the invention via a network

Third party LTE.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows a first tactical bubble B-1. In the implementation described, the networks considered are LTE networks. The first tactical bubble B-1 includes:

- A first evolved base station eNB-1,

- A first mobility manager, or MME for "Mobility Management Entity". This first mobility manager is referenced MME-1;

- A first service gateway, or SGW for "Serving Gateway".

This first service gateway is referenced SGW-1; - A first user database, or HSS for "Home Subscriber Server", ie a central database that contains information about users of the first tactical bubble. This first user database is referenced HSS-1;

- A first packet gateway, or PGW for "PDN Gateway", ie a PDN gateway "Packet Data Network". This first packet gateway is referenced PGW-1;

- A first communication policy manager, or PCRF for "Policy and Charging Rules Function", ie a manager that operates in the heart of the network and provides access to subscriber databases and databases. other specialized functions, such as a flow management system. This first communication policy manager is referenced PCRF-1.

In this document, each element described designates a device, real or virtual, equipped with data processing and communication capabilities. Such a device executes instruction codes stored in a program memory of said device according to parameters. These parameters are either stored in a data memory of said device, or received during a communication made by said device. It is noted that the same device can fulfill several functions.

Figure 1 shows that the first tactical bubble B-1 comprises a first network N-1 for interconnecting the elements of the first bubble. In particular the first network allows the establishment of links allowing the various elements to play their roles in the provision of an LTE network via the first base station. Such a network is, among other things, described by the 3GPP TS 23.401 standard defining the specifications for the "General Packet Radio Service Enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Access" (that is to say the improvements for the General Radio System (GPRS) Enhanced Universal Radio Terrestrial Access Network). Thus, FIG. 1 also shows: a first link of type S1 -C between the first base station eNB-1 and the first mobility manager MME-1; A first S1-U link between the first eNB-1 base station and the first SGW-1 service gateway;

A first link of type S1 1 between the first mobility manager MME-1 and the first service gateway SGW-1;

A first link of type S6a between the first mobility manager MME-1 and the first user database HSS-1;

A first S5 link between the first SGW-1 service gateway and the first PGW-1 packet gateway;

A first Gx-type link between the first PCRF-1 communication policy manager and the first PGW-1 packet gateway.

FIG. 1 also shows that the first tactical bubble B-1 comprises, connected to the first network N-1:

- A first orchestrator referenced 0-1. A program memory of the first orchestrator includes instruction codes for implementing the method according to the invention described below;

A first router referenced R-1;

- A first application server, referenced AF-1.

The presence of the first application server corresponds to a variant of the invention in which the first processing bubble has business processing capabilities. From this point of view, the presence or absence of an application server does not diminish or increase the bubble capacity according to the invention to federate. From the point of view of a bubble federation, the presence of an application server is therefore optional.

The orchestrator functions, in the context of the invention, are:

Ensure the discovery mode of bubbles to federate.

Identify the master orchestrator and the slave orchestrator;

Set up a secure connection between the two bubbles

Make a backup of the configuration before federation at the level of the master bubble (user base image, configuration of core network elements ...)

Retrieve or synchronize user data from the slave bubble

he - Set up the communication interfaces between the equipment of the slave bubble and the master bubble.

- Once the configuration is done, cut the links with the supernumerary elements;

- When the bubbles move away, return to the original configuration.

- A watchdog mechanism consists of performing a message exchange between the two heartbeat orchestrators ("heartbeat") or keeps alive ("keepalive"). After a predefined duration without beat, each orchestrator reconfigures all the equipment of its bubble by performing the reverse path of the federation.

- In particular, the master orchestrator performs a restoration of the image of the master user database before federation.

The first tactical bubble as described is an autonomous network bubble. That is, the first tactical bubble is self-sufficient to allow users to communicate with each other. Such a bubble is more portable, that is to say it can be deployed on any geographical position.

The addressing plan of the elements of the first tactical bubble is static and predetermined. A tactical bubble is therefore composed of at least one Evolved Packet Core (EPC), for an Evolved Network Core, an HSS / PCRF pair and an eNodeB configured in an omnidirectional LTE cell.

Figure 2 shows a second tactical bubble B-2 identical to the first tactical bubble. The second tactical bubble B-2 includes: - A second evolved base station eNB-2;

- A second mobility manager (MME-2);

- A second service gateway (SGW-2);

- A second user database (HSS-2);

- A second packet gateway (PGW-2);

- A second communication policy manager (PCRF-2). Figure 1 shows that the second tactical bubble B-2 has a second N-2 network for interconnecting the elements of the second bubble. In particular the second network allows the establishment of links allowing the various elements to play their roles in the provision of an LTE network via the second base station eNB-2. Thus Figure 1 also shows:

A second link of type S1 -C between the second base station eNB-2 and the second mobility manager MME-2;

A second S1-U type link between the second eNB-2 base station and the second SGW-2 service gateway;

A second link of type S1 1 between the second service manager MME-2 and the second service gateway SGW-2;

A second link of type S6a between the second mobility manager MME-2 and the second user database HSS-2;

A second S5 link between the second SGW-2 service gateway and the second PGW-2 packet gateway;

A second Gx-type link between the second PCRF-2 communication policy manager and the second PGW-2 packet gateway.

Figure 1 also shows that the second tactical bubble has, connected to the second network: - A second orchestrator referenced 0-2,

A second router referenced R-2;

- A second application server, referenced AF-2. The remarks made for the first application server are also valid for the second application server. The addressing plan of the elements of the second tactical bubble is static and predetermined.

In one variant of the invention, the two tactical bubbles have the same addressing scheme. The communications between the two tactical bubbles are via a network address translation (ie NAT for "Network Address Translation") one for a reciprocal at the routers. Preferably identical elements have the same host address but not the same network address. Thus any local address of the equipment and application functions of each bubble is made unique by the setting up on the external interface of the routers of an address translation rule (NAT rule) based on an identifier representative of the bubble.

In an initial state the second tactical bubble has been deployed and flows from the traffic allowing its users to communicate and access the second application server via user equipment connected to the second base station.

Following an evolution of the situation, another tactical bubble is deployed to cope with the evolution of the situation. This other tactical bubble is the one that has been described as the first tactical bubble. At first the first tactical bubble is in a blocked state, that is to say that it accepts no communication, via the first base station, from users.

Figure 3 shows a connection step 1000 in which a dedicated connection is established between the first tactical bubble and the second tactical bubble. This dedicated connection can also be described as local. This connection is made between the first router and the second router. Physically this dedicated connection is either wired or wireless (Wireless in English). A wired connection is for example an Ethernet connection, a wireless connection is for example a Wifi connection. In a variant of the invention this dedicated connection can also be achieved via a third party mobile network.

In one variant of the invention the establishment of the dedicated connection detected by the routers is followed by the establishment of an encrypted tunnel between these routers. Such a tunnel is called a VPN tunnel. Thus all the communications passing through the two routers are encrypted and thus protected against possible interception. This is the establishment of a virtual private network 200.

Once the dedicated connection is established we go to a step 1100 election of a master orchestrator. This election follows a mutual discovery. For example, such a discovery between orchestrators can rely on the multicast version of the Internet protocol (IP protocol) and on the notion of clusters (we are talking about also clusters). A multicast IP address is then known to all the bubbles able to federate which allows to join the cluster that self organizes then.

The election of a master orchestrator is a process in which the tactical bubble with the master orchestrator becomes the tactical reference bubble of the federated communication network. That is, it is the core network elements of this tactical reference bubble that will contain the entire LTE network configuration obtained by federation. According to different variants one can consider several election criteria:

- Capacity: it is the tactical bubble that has the greatest capacity to become the master bubble. A capacity is the maximum number of terminal devices that the bubble can handle simultaneously;

- Processing capacity: generic capacity of the tactical bubble, this includes welcome and business power;

- Deployment date: the first bubble, or the last, according to a predetermined convention, becomes the master bubble;

- By drawing lots,

- ... the list is not exhaustive.

In our example it is the first orchestrator who is elected master orchestrator.

It is during this election stage that the values of the identifiers of each network are also decided, as well as the zone identifiers used for searching for people (also known as paging).

It is also during this step that the translation of address one for a reciprocal is set up. In one variant, the implementation of this address translation is accompanied by the update of the registration d in the name resolution directory to allow the designation of element, for example the user database or the manager. communication policy. For example, as seen from the slave bubble, the database of the master bubble is assigned a name that can be resolved to its translated address. An alternative would be to use an address directly. Thanks to this translation and this resolution it is also possible to maintain a continuity of access to application servers regardless of the bubble to which a user equipment is connected.

In practice, each tactical bubble having a unique identifier, the value of this identifier is generally used to derive the unique values of the other parameters of the tactical bubble, in particular the translated addresses, the zone identifiers, the unique identifiers of the managers of the tactical bubble. mobilities, ... in the federation. It is therefore a setting by convention. This solution is only a non-limiting example. This unique identifier is also used during discovery.

Once the master orchestrator elected, so the master tactical bubble elected, we go to a step 1200 of updating the database of the users of the master bubble. In this step, the Orchestrators interact to copy the contents of the user database of the slave bubble into the master bubble's user database. This allows the master tactical bubble to know all the users that can connect. Each user is associated, in the user database, with his or her original bubble. This allows, for example, to return to an initial state of the user database.

In an alternative embodiment, the master orchestrator performs an image backup of the user database before the update step 1200 with the slave bubble database in order to be able to restore the user database in its database. configuration before the implementation of the federation process when the bubbles are caused to no longer be federated.

In a variant, in this step the orchestrators also update the configuration of the communication policy manager by merging the configurations of the two communication policy managers. We then go to a link configuration step 1300 in which the orchestrators configure links, according to the LTE standard, to allow the elements of the two bubbles to work together. These links are established through address translation. Thus the orchestrators configure:

A link of type S1 1 between the service gateway of the master network SGW-1 and the mobility manager of the slave network MME-2; A link of type S1 1 between the service gateway of the slave network SGW-2 and the mobility manager of the master network MME-1;

- A S10 link between the mobility manager of the MME-1 master network and the mobility manager of the MME-2 slave network;

We then go to a step 1400 update base stations for their cooperation in the federated communication network. That is, the base stations are made to collaborate in a single communication network.

In this step, each base station is updated so that the two base stations can collaborate on a handover. Each base station must know at least the "eNodeBID", the PCI and the TAC of the other base station. These elements are known as "neighborhood relations".

- eNodeBID: base station identifier;

- PCI: Physical Cell Identity for Cell Physical Identifier;

- TAC: T racking Area Code for tracing area code. It is thus necessary that each base station has a certain number of unique parameters in the future federated network: eNodeBID and PCI (orthogonal PCI to limit the radio interference). In practice the value of these parameters and obtained by convention as previously described.

We then go to a step 1500 of redundancy configuration or, in other words, configuration of the secondary elements in which the orchestrators reconfigure:

- The mobility manager of the slave tactical bubble so that its secondary user database is the user database of the master tactical bubble;

- The packet gateway of the slave tactical bubble so that its secondary communication policy manager is the communication policy manager of the master bubble.

This reconfiguration of the secondary elements is done either by declaring in the configurations an address, or a name. In a preferred variant, a name is used which will be solved according to the actions of the preceding steps. The preceding steps are in particular the steps of setting up the address translation and updating the name resolution directory records. A secondary element is an element that is used, for example, in case of unavailability of a main element.

These secondary configurations are implemented in a standard LTE network to provide resilience requirements for this type of network. In the case of the invention, these are fictitious means ("fictitious" means means diverted from their initial purpose) for the case of tactical bubbles. In the case of a normal network, these configurations are static and are not intended to be modified.

In the case of the invention, it is the orchestrators who dynamically control the change and configuration of these links pointing to secondary equipment and application functions.

At the end of step 1500 of configuration of the redundancies the orchestrators cut the links between:

- The tactical bubble slave's mobility manager and the slave tactical bubble database server

- The slave tactical bubble packet gateway is the communication policy manager of the tactical slave bubble.

These cuts cause the switchover to the secondary configuration and therefore the use, by the elements of the slave bubble, of the user database of the master bubble and the communication policy manager of the master bubble.

This leads to a federated network as represented by FIG. 2. All the users of the master and slave bubbles are recognized because the only known user database of the federated communication network is that in which the users of the federated communication network have been copied. the slave bubble.

In one variant, the method according to the invention also comprises a step 1600 for synchronizing mobility managers and service gateways so that they are aware of the existing communication contexts and thus streamline future intercellular transfers. This synchronization also makes it possible to declare in each network the service gateways and the mobility managers. In practice, in this step, it is necessary to indicate to the mobility managers the existence of the tracing zone of the other bubble as well as the address or the name of the service gateway which serves this zone. tracing.

In the invention, where appropriate, the clocks of the two networks are synchronized. At this stage you can unlock the first tactical bubble, ie allow communication via the first tactical bubble. We have therefore realized here an LTE network federation, that is to say, allowed two LTE type communication networks, not knowing each other a priori, to function as a single communication network. As it remains possible to associate each user with his original tactical bubble can also control access to application servers tactical bubbles and more generally tactical bubble resources. It is therefore possible to prohibit a user with a defined tactical bubble from accessing application servers from another bubble that is not the original tactical bubble. In one variant of the invention, all the users of all the federated tactical networks can have access to all the application functions (AF) of all the tactical networks. In another variant, the users only have access to the application functions of their original tactical network. We can also have all the crossed cases. The Orchestrator acts as a proxy for DNS name name resolution queries. Thus during a request for access to the application functions (AF) by a user equipment, a DNS request is transmitted to the orchestrator of the bubble A, which transmits it to an accessible DNS server name resolution server. associated with the bubble A. The latter returns the IP address of the server on which the application is hosted to the orchestrator, which sends it back to the user equipment.

Since the Orchestrator acts as a DNS proxy, the latter can respond differently per user for each DNS request issued by the user equipment.

It's the same for tactical bubble B During the federation of the bubble A with the bubble B, a synchronization of the DNS contexts held by each orchestrator is carried out by transfer of the DNS contexts of the slave bubble to the master bubble and vice versa. This operation can be performed in step 1200 described above.

The invention makes it possible to maintain the segmentation of the accesses to the application functions between the user equipments of the bubble A and those of the bubble B. In fact, a DNS request issued by a user equipment of the bubble A, elected bubble master to the from the federation step, will always be treated in the same way as in the case where the bubble is autonomous. On the other hand, a DNS request from a bubble B user equipment will initially be sent to the Bubble A Orchestrator who will be able to perform a name resolution to its own DNS server due to the DNS context synchronization performed during the federation or to relay the request to the orchestrator of the slave bubble according to the user equipment that issued the request.

We have described here the federation of two tactical bubbles but it is quite possible to achieve a federation between a tactical bubble is a communication network for mobile terminals of a fixed infrastructure. This ensures that a response team can communicate across the entire fixed infrastructure while being able to access its specific resources in its tactical bubble. These specific resources remain inaccessible to users originating from the fixed infrastructure network.

In practice, a federation of communication networks for mobile terminals is a communication network for mobile terminals. It is therefore possible, thanks to the invention to achieve a federation between a federated network and a communication network for mobile terminals. The invention is therefore not limited to the federation of two networks. In other words, with the invention, two communication networks for mobile terminals or more can be federated.

Figure 4 shows the first tactical bubble B-1 and the second tactical bubble B-2 federated in a context of use. Figure 4 shows:

A first user equipment 401 connected to the first tactical bubble B-1; A second user equipment 402 connected to the first tactical bubble B-1;

A third user equipment 403 connected to the second tactical bubble B-2. The third user equipment is further out of range of the base station of the first tactical bubble.

In practice, the terminal equipments are smart phones or assimilable devices, that is to say devices capable of connecting to an LTE type network.

Thanks to the invention the first user equipment, or the second user equipment, can establish communication with the third user equipment, which would be impossible without the invention. He can therefore enjoy the union of radio covers.

Note that it would be the same if the third mobile equipment was within range of the base station of the first tactical bubble. In this case it could, still thanks to the invention, use the base station of the first tactical bubble to connect to the federated network.

FIG. 5 is identical to FIG. 4 with in addition a connection between the second tactical bubble and an external network 500, for example the Internet network.

In this case, thanks to the invention, the first user terminal and the second user terminal can access the external network.

FIG. 6 is identical to FIG. 4 with one plus a third federated B-3 tactical balloon with the first tactical balloon B-1 via a dedicated link 600. FIG. 6 also shows a fourth user equipment 601 connected to the third tactical balloon B-3.

In this case, thanks to the invention, the third user equipment 403 can establish a communication with the fourth user equipment 601.

Figure 7 is identical to Figure 4 except for the dedicated connection that is made via a wireless network. In the example of Figure 7 it is a network type LTE but in practice it could act as a WiFi network. In this case each tactical bubble connects to an LTE network via a base station of said LTE network. A Once these connections established the tactical bubbles can mount the VPN 200 tunnel through these connections.

Claims

A method of federation of a first mobile terminal communication network (B-1) and a second mobile terminal communication network (B-2) each communication network comprising a base station (eNB-1, eNB-2), a mobility manager (MME-1, MME-2), a service gateway (SGW-1, SGW-2), a user database (HSS-1, HSS-2), a manager Communication Policy (PCRF-1, PCRF-2), a packet gateway (PGW-1, PGW-2) each of said networks further comprising a router (R-

1, R-2) and an orchestrator (0-1, 0-2), the method comprising the following steps:

- Establishing (1000) a dedicated connection between the two communication networks by establishing a connection between the routers;

Election (1100) of a master orchestrator among the orchestrators of the networks to be federated, defining a master network and a slave network;

- Update (1200) of the master network user database from the user database of the slave network;

- Configuration (1300) links between:

- Configuration (1500) of the slave network so that it uses:

o The user database of the master network;

o The communication policy manager of the master network.

2. A method of federation of communication networks according to one of the preceding claims characterized in that each communication network has the same addressing plan the method comprising a step in which the router of each network is dynamically configured, by the orchestrator of his network, to realize a translation of address one for a reciprocal between the two networks.

3. A method of federation of communication networks according to one of the preceding claims characterized in that it comprises the following steps:

- Update (1400) of each base station according to the neighboring base station;

- Update (1600) of the list of service gateways of each network, each service gateway being associated with a zone code according to its original network.

- Update (1600) of each mobility manager according to the configuration of the mobility manager of the neighboring network.

4. A method of federation of communication networks according to one of the preceding claims characterized in that the establishment of the dedicated connection is achieved by the use of a connection means belonging to the list consisting of at least:

- A cable,

- Wireless connection.

5. The method of federation of communication networks according to one of the preceding claims characterized in that the communications made via the dedicated connection are using a virtual private network.

6. A method of federation of communication networks according to one of the preceding claims, characterized in that the use by the slave network elements of the master network is not the configuration in the slave networks of the secondary elements.

7. The method of federation of communication networks according to claim 6, characterized in that the configuration of the secondary elements is done by naming, the resolution of the names being configured by the network orchestrator at the time of the federation.

8. The method of federation of communication networks according to one of the preceding claims, characterized in that a communication network for mobile terminals is an autonomous network bubble.

9. The method of federation of communication networks according to one of the preceding claims, characterized in that the election of the master orchestrator is based on the capacity of reception and treatment of the bubble to which the orchestrator belongs.

10. The method of federation of communication networks according to one of the preceding claims, characterized in that access to the application functions of a bubble is maintained and is limited to its original users.

11. A communication network for mobile terminals, said first network, adapted to be federated, with a second communication network for mobile terminals adapted to be federated, a communication network for mobile terminals adapted to be federated comprising a base station, a a mobility manager, a service gateway, a user database, a communication policy manager, a packet gateway each communication network further comprising a router and an orchestrator, said first communication network being configured to:

- Elect a master orchestrator among the orchestrators of the first and second networks to federate, defining a master network and a slave network;

- Configure links between:

o The service gateway of the master network and mobility manager of the slave network;

o The packet gateway of the master network and the service gateway of the slave network;

- Configure the slave network to use:

o The user database of the master network;

o The communication policy manager of the master network.

12. Communication network according to claim 11 characterized in that it is an autonomous network bubble.